Hi everyone,
I am trying to identify vesicles at different stages in the autophagic pathway in the heart, especially autophagosomes. However, the EM quality seems good, but I can rarely see autophagosomes in starved heart; I do see many large blank vesicles and some very small vesicles with irregular contents which are not electronic dense.
Does anyone have suggestions on literature with good EM pictures on autophagosomes? Does anyone know if heart is different from other organs in terms of forming autophagosome? (I mean, since the sarcomere is so densely packed with myofilaments and mitochondria)
Thanks in advance!
Hi Nancy,
Morphological criteria for identification of autophagic vesicles (AVs) included (i) circularity (ii) contrast with structures that were white or lighter than the cytoplasm (iii) vesicles with contents (iv) vesicles more than 200 nm in size and (v) double membrane structure.
Cellular structures which resemble AVs such as mitochondria and pigment containing vesicles can be excluded from counting based on their different characteristics as described previously by Ma et al., 2011 (Measurements of tumor cell autophagy predict invasiveness, resistance to chemotherapy, and survival in melanoma).
Regards
Dear Nancy Liu,
Mónica Suárez Korsnes already sent you links to several of my articles that may answer your question. Please contact me if you have problems getting full text of these articles. You can also send some of your EM images to me, and I will tell you my interpretations.
Eeva-Liisa Eskelinen
This is a very good publication: http://www.ncbi.nlm.nih.gov/pubmed/24924129
It is indeed rather difficult to see autophagosomes in heart tissue, a better alternative would be to look at the liver. Autophagosomes are not blank so I believe you can rule those vesicles out. There should be some content in them. I have attached some TEM pictures from my own research (heart tissue, mice treated with everolimus + chloroquine), in image 1 you can see autophagosomes as they should be (upper left), in image 2 the blank and opake vesicles which I don't count as autophagosomes. Good luck!
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